Setting thermostat controls by measuring the temperature will result in the ________ highest energy costs. Response:

Measuring at the server inlet is generally considered the most efficient method as it ensures that critical components receive air within optimal temperature ranges, leading to lower energy costs.

When thermostat controls are set based on return air temperature, the cooling system attempts to cool the entire volume of air in the data center until the warmest air returning to the CRAC unit meets the setpoint. This often leads to overcooling certain areas and requires the cooling system to run longer and consume more energy compared to sensing at critical points like server inlets.

Measuring under-floor temperature, while sometimes used, is not a direct measure of air reaching equipment and can be inefficient, but typically less wasteful than return air sensing.

External ambient temperature is unrelated to internal data center cooling efficiency and is not used for direct thermostat control within the facility.